DTC P0729
Diagnostic Instructions
DTC Descriptor
DTC P0729: 6th Gear Ratio Incorrect
Diagnostic Fault Information
Component
|
Condition
|
DTCs
|
Valve Body Assembly
|
• |
Incorrect transmission fluid level |
• |
Clogged hydraulic system |
• |
Plugged or restricted passages |
|
P0729, P0731, P0732, P0733, P0734, P0735, P0736, P0780,
P1731
|
Line Pressure Control Solenoid Valve
|
• |
Incorrect transmission fluid level |
• |
Clogged hydraulic system |
• |
Mechanically stuck in the applied position |
|
P0729, P0731, P0732, P0733, P0734, P0735, P0736, P0780,
P1731
|
Shift Solenoid Valve
|
• |
Incorrect transmission fluid level |
• |
Clogged hydraulic system |
• |
Mechanically stuck in the applied position |
|
P0729, P0731, P0732, P0733, P0734, P0735, P0736, P0780,
P1731
|
Pressure Control Solenoid Valve
|
• |
Incorrect transmission fluid level |
• |
Clogged hydraulic system |
• |
Mechanically stuck in the applied position |
|
P0729, P0731, P0732, P0733, P0734, P0735, P0736, P0780,
P1731
|
Fluid Pump Cover Assembly
|
Fluid pump cover vanes and fluid pump rotor broken
|
P0729, P0731, P0732, P0733, P0734, P0735, P0736, P0780,
P1731
|
Circuit/System Description
The shift control solenoid assembly (SLC1, SLC2, SLC3,
SLB1) and the line pressure control solenoid (SLT) are
installed on the front valve body. The solenoids linearly control
hydraulic pressure in response to signals output from the
transmission control module (TCM). SLC1, SLC2, SLC3, SLB1
controls hydraulic pressure to the clutches (C1, C2, C3) and
brake (B1) for smooth shifting. According to each shift
control solenoid assembly, the transmission shifts from 1st gear to
6th gear and vice versa. As a fail-safe function, if any shift
control solenoid assembly abnormality occurs, the TCM will disable
the current to the solenoids.
Conditions for Running the DTC
• |
The ignition voltage is 10.2-15.5 V. |
• |
The engine speed is greater than 400 RPM for
2 s. |
• |
The transmission is not in emergency mode. |
• |
TCM communication is normal. |
• |
Transmission fluid temperature is higher than
20°C (68°F). |
• |
DTCs P0716. P0717, P0721 and P0722 are not
set. |
Conditions for Setting the DTC
• |
Driving in D range, 6th gear. |
• |
Output speed more than 500 RPM. |
• |
Throttle position more than 10%. |
• |
Measured gear ratio deviates more than 20% from
expected ratio. |
• |
Measured gear ratio deviates within 4% from 4th or
5th gear ratio. |
• |
Determined after 12 times lasting 1 s or
more. |
Action Taken When the DTC Sets
• |
DTC P0729 is a Type C DTC. |
• |
Torque limitation in "D" range
150 N·m (110 lb ft), in "R" range
170 N·m (125 lb ft). |
• |
The TCM freezes transmission adaptive
functions. |
• |
The TCM turns OFF all solenoids. |
• |
The TCM allows the vehicle to operate only in the
second gear and "R" range after a stop. |
Conditions for Clearing the DTC
• |
DTC P0729 is a Type C DTC. |
• |
Measured gear ratio deviates less than 4% from
expected ratio. |
Diagnostic Aids
Ensure the transmission fluid level, color and odor is correct
and there are no leaks. If there are any other transmission DTCs
set, diagnose those first.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
Description and Operation
Transmission Component and System Description
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Verify the transmission fluid level, color and odor is
correct.
- Operate the vehicle to induce a shift from fifth to
sixth gear while observing the following scan tool parameters. The
scan tool parameters has to change the proper value referring to
the current gear, compare the proper values with: transmission
system description and operation. Refer to
Transmission System Description and Operation . Perform this
action 2 times.
• |
Clutch Pressure Control Solenoid Valve 1
Current |
• |
Clutch Pressure Control Solenoid Valve 2
Current |
• |
Clutch Pressure Control Solenoid Valve 3
Current |
• |
Brake Band Pressure Control Solenoid Valve
Current |
If the scan tool parameter does not change the proper value and
no other DTCs than P0729, P0731, P0732, P0733, P0734, P0735, P0736,
P0780, P1731 is set, go to Circuit/System Testing.
If any other DTC is set, diagnose that DTC first.
Circuit/System Testing
Dynamic Test
- Perform the line pressure check. Refer to
Line Pressure Check .
- Perform the transmission fluid check. Refer to
Transmission Fluid Level and Condition Check .
- If all circuits test normal, replace the
K71 Transmission Control Module. Verify the DTC does not
reset.
If the DTC resets replace the control valve body.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
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